This invention relates to a pneumatic pipe plug typically used to block or divert the flow in municipal or commercial pipe. A pneumatic pipe plug operates by inflating an expandable bladder which expands against the inside wall of the pipe. Typically, the pipe can range from inches to many feet in diameter. The pneumatic pip plug remains in place by the frictional forces generated between the expanded bladder and the inside wall of the pipe. As used herein, the term xe2x80x98pipe plugxe2x80x99 includes a flow diverter in which the normal flow of the fluid in the pipe is blocked and directed to a smaller flow through conduit and typically redirected to a recovery or disposal location through a connected hose.
In fabricating a pneumatic pipe plug the interconnection of the pneumatic bladder and the rigid end structure of the plug is problematic. Customarily, the expandable bladder is formed with an end that is custom formed and wrapped over and around rigid end plates which include anchor means to control the pipe plug and fittings to provide for supply of air or other gas to the pipe plug during inflation.
The pipe plug is typically used in an environment that is unpredictable and may be critical to the safety of workers, for example, in a municipal sewer pipe line that is blocked with a pipe plug to allow repair men to enter and repair a segment of pipe. In such environments, the pipe plug must be versatile, rugged and highly resistant to failure. In order to meet this challenge, conventional pneumatic pipe plugs are in part hand fabricated which adds substantially to the resultant cost. Problems in fabricating pipe plugs for larger diameter pipe are compounded by the aggregate forces applied to the plug from even moderate fluid pressures. In typical drainage pipe systems, the pipe plug must withstand a ten foot water head and similar pressures from fluids and other environments are expected to be encountered.
It is the object of this invention to construct production pneumatic pipe plugs that perform in the expected environment as well as hand crafted pneumatic pipe plugs. By elimination of the hand forming of the pneumatic bladder forming the body of the pipe plug, substantial savings in fabrication costs can be achieved.
The pneumatic pipe plug of this invention is designed to reduce the fabrication time and costs of producing a pneumatic pipe plug without compromising the versatility, durability and/or safety of the resultant plug. The compressed-ring pneumatic pipe plug of this invention has a body in the form of a pneumatic bladder with rigid end caps. The end caps are constructed with circular end plates with a rigid perimeter rim over which end cuffs of the pneumatic bladder are installed. A ring substantially matching the rim is positioned over the end cuffs and rim and compressed by high pressure swaging device. The end cuffs of the expandable bladder are thereby sandwiched between the peripheral contact surface of the rim and the inner contact surface of the ring. To prevent the forces of the expanding bladder from peeling the ring off from the rim, the outer contact surface of the rim is provided with a ridge and the inner contact surface of the ring is provided with a complimentary groove. It is to be understood that the opposite arrangement with a groove in the rim and a ridge in the ring provides an equivalent structure to lock the ring to the rim when the rim is compressed when swaging. Multiple grooves and ridges can be provided to accomplish this function.
The circular end plates can be fitted with or tapped for fittings according to the prospective usage of the plug.